# NSThread class reference

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mccallum@gnu.ai.mit.edu
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Generated at 2025-02-13 06:02:40 +0000
1996-2018 Free Software Foundation, Inc.
Software documentation for the NSThread class
Foundation/NSThread.h
This class encapsulates OpenStep threading. See NSLock and its subclasses for handling synchronisation between threads.
Each process begins with a main thread and additional threads can be created using NSThread. The GNUstep implementation of OpenStep has been carefully designed so that the internals of the base library do not use threading (except for methods which explicitly deal with threads of course) so that you can write applications without threading. Non-threaded applications are more efficient (no locking is required) and are easier to debug during development.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.
callStackReturnAddresses
Returns an array of the call stack return addresses.
currentThread

Returns the NSThread object corresponding to the current thread.

NB. In GNUstep the library internals use the GSCurrentThread() function as a more efficient mechanism for doing this job - so you cannot use a category to override this method and expect the library internals to use your implementation.

detachNewThreadSelector:
aSelector
toTarget:
aTarget
withObject:
anArgument

Create a new thread - use this method rather than alloc-init. The new thread will begin executing the message given by aSelector, aTarget, and anArgument. This should have no return value, and must set up an autorelease pool if retain/release memory management is used. It should free this pool before it finishes execution.

exit
Terminates the current thread.
Normally you don't need to call this method explicitly, since exiting the method with which the thread was detached causes this method to be called automatically.
isMainThread
Returns a boolean indicating whether this thread is the main thread of the process.
isMultiThreaded
Returns a flag to say whether the application is multi-threaded or not.
An application is considered to be multi-threaded if any thread other than the main thread has been started, irrespective of whether that thread has since terminated.
NB. This method returns `YES` if called within a handler processing `NSWillBecomeMultiThreadedNotification`
mainThread
Returns the main thread of the process.
setThreadPriority:
pri
Set the priority of the current thread. This is a value in the range 0.0 (lowest) to 1.0 (highest) which is mapped to the underlying system priorities.
sleepForTimeInterval:
ti
Suspends execution of the process for the specified period.
sleepUntilDate:
date
Delaying a thread... pause until the specified date.
threadPriority
Return the priority of the current thread.
cancel
Cancels the receiving thread.
init
Description forthcoming.
initWithTarget:
aTarget
selector:
aSelector
object:
anArgument
Initialises the receiver to send the message aSelector to the object aTarget with the argument anArgument (which may be `nil`).
The arguments aTarget and aSelector are retained while the thread is running.
isCancelled
Returns a boolean indicating whether the receiving thread has been cancelled.
isExecuting
Returns a boolean indicating whether the receiving thread has been started (and has not yet finished or been cancelled).
isFinished
Returns a boolean indicating whether the receiving thread has completed executing.
isMainThread
Returns a boolean indicating whether this thread is the main thread of the process.
main
FIXME... what does this do?
name
Returns the name of the receiver.
setName:
aName
Sets the name of the receiver.
setStackSize:
stackSize
Sets the size of the receiver's stack.
stackSize
Returns the size of the receiver's stack.
start
Starts the receiver executing.
threadDictionary
Return the thread dictionary. This dictionary can be used to store arbitrary thread specific data.
NB. This cannot be autoreleased, since we cannot be sure that the autorelease pool for the thread will continue to exist for the entire life of the thread!
Software documentation for the NSObject(NSThreadPerformAdditions) category
Foundation/NSThread.h
Extra methods to permit messages to be sent to an object such that they are executed in another thread.
The main thread is the thread in which the GNUstep system is started, and where the GNUstep gui is used, it is the thread in which gui drawing operations must be performed.
performSelector:
aSelector
onThread:
aThread
withObject:
anObject
waitUntilDone:
aFlag
Invokes -performSelector:onThread:withObject:waitUntilDone:modes: using the supplied arguments and an array containing common modes.
These modes consist of NSRunLoopMode, NSConnectionreplyMode, and if in an application, the NSApplication modes.
performSelector:
aSelector
onThread:
aThread
withObject:
anObject
waitUntilDone:
aFlag
modes:
anArray

This method performs aSelector on the receiver, passing anObject as an argument, but does so in the specified thread. The receiver and anObject are both retained until the method is performed.

The selector is performed when the runloop of aThread next runs in one of the modes specified in anArray.
Where this method has been called more than once before the runloop of the thread runs in the required mode, the order in which the operations in the thread is done is the same as that in which they were added using this method.

If there are no modes in anArray, the method has no effect and simply returns immediately.

The argument aFlag specifies whether the method should wait until the selector has been performed before returning.
NB. This method does not cause the runloop of aThread to be run... so if the runloop is not executed by some code in aThread, the thread waiting for the perform to complete will block forever.

As a special case, if aFlag == `YES` and the current thread is aThread, the modes array is ignored and the selector is performed immediately. This behavior is necessary to avoid the current thread being blocked by waiting for a perform which will never happen because the runloop is not executing.

performSelectorInBackground:
aSelector
withObject:
anObject
Creates and runs a new background thread sending aSelector to the receiver and passing anObject (which may be `nil`) as the argument.
performSelectorOnMainThread:
aSelector
withObject:
anObject
waitUntilDone:
aFlag
Invokes -performSelectorOnMainThread:withObject:waitUntilDone:modes: using the supplied arguments and an array containing common modes.
These modes consist of NSRunLoopMode, NSConnectionReplyMode, and if in an application, the NSApplication modes.
performSelectorOnMainThread:
aSelector
withObject:
anObject
waitUntilDone:
aFlag
modes:
anArray

This method performs aSelector on the receiver, passing anObject as an argument, but does so in the main thread of the program. The receiver and anObject are both retained until the method is performed.

The selector is performed when the runloop of the main thread next runs in one of the modes specified in anArray.
Where this method has been called more than once before the runloop of the main thread runs in the required mode, the order in which the operations in the main thread is done is the same as that in which they were added using this method.

If there are no modes in anArray, the method has no effect and simply returns immediately.

The argument aFlag specifies whether the method should wait until the selector has been performed before returning.
NB. This method does not cause the runloop of the main thread to be run... so if the runloop is not executed by some code in the main thread, the thread waiting for the perform to complete will block forever.

As a special case, if aFlag == `YES` and the current thread is the main thread, the modes array is ignored and the selector is performed immediately. This behavior is necessary to avoid the main thread being blocked by waiting for a perform which will never happen because the runloop is not executing.

Software documentation for the NSThread(CallStackSymbols) category
Foundation/NSThread.h
Description forthcoming.
callStackSymbols
Returns an array of NSString objects representing the current stack in an implementation-defined format. May return an empty array if this feature is not available.
Software documentation for the NSThread(GSLockInfo) category
Foundation/NSThread.h
Description forthcoming.
mutexDrop:
mutex
Description forthcoming.
mutexHold:
mutex
Description forthcoming.
mutexWait:
mutex
Description forthcoming.